Boiler construction



Oct. 25, 1932. KLEFFEL 1,884,742

BOILER CONSTRUCTION Filed March 25, 1931 2 Sheets-Sheet 1 13: 1, J gE,

I INVENTOR.

"i 7% W M Mr :4TTORNEYS.

Oct. 25, 1932.

H. E. KLEFFEL BOILER CONSTRUCTION Filed March 25, 1951 2 Sheets-Sheet 2 IN VEN TOR.

W ATTORNEYS.

Patented Oct. 25, 1932 PAT nr scarier.

HARRISON E. KLEFFEL, OF NEW YORK, N. Y.

BOILER CONSTRUCTION Application filed March 25, 1931. Serial No. 525,143.

This invention relates to steam boilers, and is concerned more particularly with a novel system of interchangeable tube structures adapted to be used in boiler installations to provide a tube bank disposed beyond the furnace cavity either directly in front of the convection tubes forming a part of the boiler or in front of a superheater therein or located within the furnace cavity directly above the fuel bed or fuel entrance and in the zone of combustion. Each tube structure forming part of the novel system includes a pair of headers and a row of spaced heatabsorbing tubes extending between these headers. The tube structures may be of several types in which the tube spacing differs and by a proper selection and arrangement of the structures in the bank, the gas passages through the bank may be arranged to produce the best results in accordance with varying types of fuel being consumed and to obtain the most efiicient distribution of the heating surface.

In my co-pending application, Serial No.

" $39,349, filed March 27 1930, I have disclosed a boiler installation in which heatabsorbing tubes are disposed in the furnace cavity in the zone of combustion. The tubes employed for this purpose have a covering selected to control the rate of heat transfer to the tube contents and the tubes produce turbulence in the burning gases and destroy stratification thereof so that a more com plete and more rapid combustion is obtained.

In employing tubes for the purpose described in my prior application or in a bank at the top of the furnace cavity and just in front of convection tubes or a superheater it is evident that the spacing and arrangement of the tubes should be varied in accordance with the type of fuel being used in order to obtain the best results. While these tubespreferably have a relatively wide spacing in all instances, at least in a direction transverse to the path of travel of the gases, the spacing and arrangement employed with oil or gas should be somewhat different from those used where pulverized fuel or solid fuel of a type which produces a large amount of fine particles of solid material passing up through the boiler surfaces are being burned. With the latter fuels, particles of molten ash or slag are likely to adhere to the tubes and consequently the tubes should be so arranged as to provide a relatively free flow of the gas to prevent the particles of slag from build ing up in the tube bank.

The system of interchangeable tube StIl1U-- tures of the present invention may be used in the furnace cavity in the zone of combustion as set forth in my prior application or may be used at the top of the furnace cavity. In either instance, the new system makes it possible to vary the spacing and arrange ment of the tubes in the bank in the field and without interfering to any substantial ex tent with the continuous use of the boiler.

For a better understanding of my inven tion, reference may be had to the accompanying drawings, in which Fig. 1 is a vertical sectional view of a typical water tube boiler of the cross-drum type, provided with a tube bank made up of the interchangeable units of my invention;

Fig. 2 is a view in elevation of the boiler shown in Fig. 1; V

Fig. .3 is a transverse sectional view through a tube bank constructed of the units of my invention;

Figs. 4, 5 and 6 are views similar to Fig. 3 showing different arrangements of the tubes in the bank;

Fig. 7 is a vertical sectional view of a detail of the bank showing certain features of the installation;

Fig. 8 is a vertical section of a boiler similar to that shown in Fig. 1, but provided with a superheater and having a tube bank of my invention disposed in the furnace cavity within the zone of combustion;

Fdig. 9 is a view on the line 9-9 of Fig. 8; an

Fig. 10 is a view of a modified form of certain parts shown in Fig. 8.

Referring now tothe drawings, the boiler shown in Fig. 1 includes a drum 10 provided with downtake headers 11 and uptake headers 12, the latter being connected to the drum by circulating tubes 13. Extending between the headers are tubes 14 inclined slightly to the horizontal and forming a convection bank. The boiler circulation is downward from the drum 10 in the downtake headers 11, then upwardly through tubes 14 in the bank and the uptake headers 12 and thence through the circulating tubes 13 to the drum. Disposed across the bank are baffles 15 and 16 which guide the products of combustion through the bank in a tortuous path.

The boiler and interchangeable headers and tubes are disposed above a furnace cavity 17 which is provided with a front wall 18, rear wall 19, and side walls 20. As illustrated, the furnace is provided with a burner 21 of a conventional type and this burner may be for oil, gas, or powdered coal.

In the installation shown in Fig. 1, I provide a tube bank generally designated 22 and below the convection tubes 14. This bank is made up of a plurality of interchangeable tube structures or units, each unit comprising a pair of headers 23 and tubes 24 connecting the headers. These units are so disposed that the headers lie substantially horizontal and extend substantiallytransverse to the direction of flow of the gases. The tubes may be straight or bent, straight tubes being preferred. In the construction illustrated there are six such units, each unit being structurally independent of the others. The units in the bank illustrated are of two types, one kind of unit having six tubes 24 and the other five such tubes. The headers of the units extend across the front and rear walls of the furnace from side to side and each header is connected by suitable piping 25 and 26 to manifolds 27 and 28, respectively. Manifold 27 is connected to the drum 10 by a downcomer pipe 29 and the manifold 28 is connected to the drum by a riser pipe 30. Connections 25 and 26 include suitable unions so that the header units may be readily disconnected from the manifolds, and the manifolds are connected to the pipes 29 and 30 by unions so that the manifolds can be quickly removed and replaced.

The tube units which comprise the bank of tubes at the top of the furnace cavity are interchangeable so that the spacing and arrangement of the tubes in the bank may be varied to suit the conditions of operation and the best disposal of the heating surface for the various fuels being consumed may be obtained. In the construction illustrated in Fig. 3, the five-tube units 31 and six-tube units 32 are disposed alternately so that the tubes of adjacent units are staggered and the products of combustion passing through the tubes of the bank change direction repeatedly so that each tube is exposed to the maximum amount of heat. This arrangement is probablymost advantageous when gas or oil is being burned in the furnace.

In the construction illustrated in Fig. 4:, there are six units in the bank arranged in two groups. The units in the lower group, generally designated 33, are of the five-tube type and those in the upper group, generally designated .34, are of the six-tube type. The units of each group are spaced relatively closely, while the two groups of units have a somewhat wider spacing in a vertical direction. In such a bank, there are vertical rows of tubes in a staggered arrangement and the products of combustion pass parallel to the rows of tubes in their travel to the convection tubes of the boiler. This spacing and arrangement of the tubes is likely to prove most advantageous in connection with the burning of powdered fuel or when stokers are employed, and a large amount of fine particles of coal and ash are discharged into the furnace cavity and pass up through the boiler. With the tubes arranged in the bank as disclosed in Fig.4, particles of molten ash or slag which adhere to the tubes will have a tendency to run down the tubes in the different rows and then drop from the lowermost tube in each'row directly in the furnace without clogging the gas passages between the tubes.

Another arrangement of the tubes in the bank is illustrated in Fig. 5. Here, the lowest headers 35 are of the six-tube type and these headers are placed relatively closely in a vertical direction and at a somewhat greater spacing from the next pair of headers 36 which are of the five-tube type; Above the headers 36 are headers 37 and 38 of the sixand five-tube variety, respectively, and spaced a substantial distance apart. In this bank, there are vertical rows of tubes provided by the two lowest headers 35,- and other rows provided by headers 36, which rows are staggered with relation to the rows of the lowest pair ofheaders. Above the headers 36 are individual tubes in staggered arrangement. The construction shown in Fig. 5 may be used when coal is burned on .stokers, by hand firing or inpulverized form.

In the construction shown in Fig. 6, the arrangement is somewhat similar to that illustrated in Fig. 3 but the headers 31 and 32 in the lower part of the bank have a greater separation vertically than those in the upper part of the bank. This arrangement gives satisfactory results in connection with oil, gas, and certain types of coal.

In Fig. 7 there is illustrated the manner in which the tube units are spaced apart vertically. The units may be mounted in a suitable support and separated by spacing blocks 39 which may be'of varying thickness and used singly or in combination to provide the desired vertical spacing of the units.

In any of the arrangements above described, it will be evident that the units are individually removable. This operation merely requires disconnection of the piping connections to the manifolds, after which the units can be removed separately, transposed if desired, and replaced. The removal and transposition of the units in order to effect a variation in the tube spacing and arrangement in the bank is a simple matter and can be accomplished in a short time in the field and such changes as may be necessary to produce the best results with different types of fuel do not require that the boiler be idle for substantial periods.

In Figs. 8, 9, and there is illustrated an installation of the interchangeable tube units Within the combustion zone of the furnace, the tubes being located within and extending across the furnace cavity in the Zone of combustion and directly over the fuel bed or the point of admission of the fuel. Such tubes promote turbulence in the burning gases and avoid stratification so that more rapid and more nearly complete combustion in the furnace cavity is obtained. Such tubes in accordance with the disclosure of my copending application previously identified are preferably provided with a covering selected to control the amount of heat absorbed therein so that the tubes do not withdraw heat from the burning gases to such an extent as to interfere with complete combustion thereof.

In the arrangement as illustrated in Fig. 8.

- the interchangeable units include headers provided with rows of tubes 41, these tubes preferably bein covered as disclosed in my prior application. The headers are connected to the drum 10 by downcomer pipes 42 andby riser pipes 43. The bank made up of the interchangeable units lies in the furnace cavity 44 a short distance above the burner 45 so that the tubes 41 lie in the zone where com bustion is taking place. The headers are preferably of two or more kinds differing among themselves in the spacing and. arrangement of the tubes by which the headers are connected. As shown more clearly in Fig. 9, the lowermost header 46 is provided with a row of tubes 47 which are staggered with relation to the tubes 48 of the header 49 next above. This alternate arrangement of the tubes continues throughout the bank and each tube unit is provided with tubes such as those designated 50, near the ends of the header, the tubes 50 lying close to the side walls 51 of the furnace chamber and serving to protect the side walls.

It will be evident that the interchangeable headers illustrated in Figs. 8 and 9 can be transposed and rearranged to provide a multiplicity of tube spacings and arrangements in the bank similar to those illustrated in Figs. 3 to 6, inclusive. Various arrangements and tube spacings may be employed in order to obtain the best results with different kinds of fuel and to obtain the most efficient distribution of the heating surface within the furnace cavity. In all instances, the tube units are readily removable and replaceable and can be transposed and rearranged in the field to provide a bank having the desired gas passages through it without necessitating an considerable period of idleness of the boiler.

The tubes in the bank 22 in all cases absorb a relatively large amount of heat and in some instances it may be desirable to provide each unit in the bank consisting of a pair of headers and their connecting tubes with separate downcomer pipes 42 and riser pipes 43 for the supply of water to and the discharge of water, steam, and vapor from the tube units, as shown in Figs. 8 and 9. In other installations, the construction illustratedin Fig. 10 is satisfactory, this construction involving the use of headers 53 which are connected by pipes 54 to manifolds 55.

hile I have illustrated the system of in tel-changeable tube units as including headers extending horizontally from side to side of the furnace, it will be apparent that instead of using single horizontal headers, each such header may be made up of sections, and these sections may be interchanged.

My bank of tubes which includes the removable and interchangeable units consisting in each instance of a pair of headers and tubes connected thereto provides for varying conditions of operation. Since I employ units of two different types in the bank, as, for example, units 81, in which there are an odd number of tubes and units 32, in which there are an even number of tubes, and these units are readily interchangeable, it will be apparent that the units can be arranged to present a greater or less amount of available heating surface to the direct contact of the flame and gas passing through the bank. Also, the amount of surface exposed to radiant heat may be increased or reduced and, therefore, by interchanging or rearranging the header and tube units in the bank it is possible to increase or diminish the total heat absorption of the surface in the bank. The units can be arranged to increase the resistance to the flow of the flame and through the bank and this insures increased turbulence of the gases. when the units are arranged to decrease the resistance to flow, they may permit a relatively free flow of the flame and the gases to the convection heating surface. The units can further be arranged so that a portion of the bank will offer a relatively large resistance to flow and the remainder of the bank will offer a relatively small resistance to flow. A bank of relatively free flow will be used in those cases in which combustion is substantially complete by the time the gases reach the bank. here the tubes in the bank lie within the zone where the combustion is continuing and thus serve the purpose of creatin turbulence in the stream and thereby accelerating combustion, it is preferable to provide the tubes with a covering to control the amount of heat absorbed thereby and thus 1 iii) 1 the bank.

changeable units is above or directly in the furnace cavity, so that the heat absorption by this surface will be at a relatively high rate and consequently the tubes in the bank will be subjected to severe service. Therefore,

' easy removal of the surface in this bank is a decided advantage and with the construction which I have disclosed, the tube units can be readily withdrawn from the boiler setting for inspection. It is especially desirable that the tube units be easily removed for such inspection when the tubes are covered and with my construction,inspection and repair of the units can be quickly effected in a short time after the boiler is shut down. Moreover, the units are exposed to service of varying degrees of severity. in different parts of the bank and the interchangeability afforded by my construction permits those units which have been subjected to the severest service to be interchanged with those exposed to less severe conditions, thus increasing the average life of the bank as a whole.

When the interchangeable bank is used with aboiler having a superheater located in the path of the gases, the arrangement of the heating surface in the bank may be varied to increase or decrease the total heat absorption by the bank and thus increase or decrease the temperature of the gases leaving This makes it possible to vary the amount of superheat as well as the total temperature of the steam leaving the boiler in an installation including a superheater having a given location and a fixed amount of heating surface.

It will consequently be apparent that with the system of interchangeable tube units described, the units may be arranged in the bank to produce best results as the type of fuel and method of firing vary. Also, the arrangement of the units in the bank is adapted to provide'best results with boiler furnaces of different types.

I claim:

1. In a boiler installation, the combination of a furnace chamber, means for introducing fuel into the chamber for ignition and combustion therein, heat absorbing surface beyond the furnace chamber in the direction of flow of the gases of combustion, and a bank of tubes within the furnace chamber made up of a plurality of interchangeable units, each unit including a pair of headers extending substantially at right angles to the direction of gas flow and tubes connecting the headers and the units in the bank including at least two kinds-differing in the locations of the tubes within the furnace chamber when the units are in place therein, whereby replacing a unit of one kind by a unit of the other kind produces a variation in the amount of heat absorbed by the bank and a variation in the resistance to gas flow offered by the bank.

2. In a boiler installation, the combination of a furnace chamber, means for introducing fuel into the chamber for ignition and combustion therein, heat absorbing surface beyond the furnace chamber in the direction of flow of the gases of combustion, and a bank of tubes disposed between the furnace chamber and said heat absorbing surface, said bank being made up of aplurality of interchangeable units, each unit including a pair of headers extending substantially at right angles to the direction of gas flow and tubes connecting the headers, and the units in the bank including at least two kinds differing in the locations of the tubes relative to the headers, whereby replacing a unit of one kind with a unit of the other kind produces a variation in the amount of heat absorbed by the bank and a variation in the resistance to gas flow offered by the bank.

3. In a boiler installation, the combination of a furnace chamber, means for introducing fuel into the chamber for ignition and combustion therein, heat absorbing surface beyond the furnace chamber in the direction of flow of the gases of combustion, and a bank of tubes within the furnace chamber made up of a plurality of interchangeable units, each unit including a pair of headers extending substantially at right angles to the direction of gas flow and'tubes connecting the headers, said tubes being covered from end to end within the furnace chamber by coverings restricting the absorption of heat by the tube contents, and the units in the bank including at least two kinds differing in the locations of the tubes relative to the headers, whereby substituting a unit of one kind for a unit of the other kind produces a variation in the amount of heat absorbed by the bank and a variation in the resistance to gas flow ofi'ered by the bank.

4. In a boiler installation, the combination of a furnace chamber, means for introducing fuel into the chamber for ignition and combustion therein, heat absorbing surface beyond the furnace chamber in the direction of flow of the gases of combustion, and a bank of tubes within the furnace chamber made up of a plurality of interchangeable units, each unit comprising a pair of headers extending substantially at right angles to the direction of gas flow and a row of tubes connecting the headers and said bank including units of at least two different kinds, the tubes having the same center to center spacing in each kind of unit but the arrangement of the tubes differing in the two units, whereby the amour of heat absorbed by the tube surface in the bank and the resistance to gas flow offered by said bank may be varied by substituting units of one kind for units of the other kind.

5. In a boiler installation, the combination of a furnace chamber, means for introducing fuel into the chamber for ignition and combustion-therein, heat absorbing surface beyond the furnace chamber in the direction of flow of the gases of combustion, and a bank of tubes Within the furnace chamber made up of a plurality of interchangeable units, each unit comprising a pair of headers extending substantially at right angles to the direction of gas flow and a row of tubes connecting the headers, the units being of at least two different kinds with the tubes uniformly spaced in both kinds of unit but one unit having an even number of tubes and the other an odd number of tubes, whereby the amount of heat absorbed in the bank and the resistance to gas flow offered by the bank can be varied by substituting units of one kind for units of the other kind.

6. In a boiler installation, the combination of a furnace chamber, means for introducing fuel into the chamber for ignition and combustion therein, heat absorbing surface beyond the furnace chamber in the direction of flow of the gases of combustion, and a bank of tubes within the furnace chamber made up of a plurality of interchangeable tube units, each unit comprising a pair of horizontal headers lying at opposite sides of the furnace chamber and a row of tubes extending across the furnace chamber and connected to the headers, the units in the bank being of at least two kinds differing in the locations of the tubes relative to the headers, whereby resistance to gas flow through the bank can be varied by substituting units of one kind in the bank for units of the other kind.

7. In a boiler installation, the combination of a furnace chamber, means for introducing fuel into the chamber for ignition and combustion therein, heat absorbing surface be yond the furnace chamber in the direction of flow of the gases of combustion, a bank of tubes within the furnace chamber made up of a plurality of interchangeable units, each unit comprising a pair of headers disposed at opposite sides of the furnace chamber and extending substantially at right angles to the direction of gas flow, and a row of tubes connecting said headers, the units in said bank 55 being of at least two styles differing in the location of the tubes with respect to the headers, whereby the interchanging of unlike units results in a variation in the amount of heat absorbed in said bank and the resistance to to flow of gases through said bank offered by said bank, said units being arranged one above another in said bank, and means for varying the spacing between said units.

In testimony whereof I affix my signature.

HARRISON E. KLEF F EL. 

